Chemical pollution is the latest calamity as heavy rains continue to blanket the country with severe flooding.

Flooding from torrential rains has washed more than 1,000 barrels of explosive chemicals into the Songhua River in northeastern China, Reuters reports. The chemicals have caused officials to shutdown water supplies to more than 4 million people, while the overflowing river has trapped nearly 30,000 people in Jilin city, the BBC reports.

This is the worst flooding China’s experienced in more than a decade as a heavier than normal monsoon season has hit the country—leaving 928 people dead, 477 missing and causing nearly $US26 billion dollars in losses, according to the latest statistics released by the State’s Office of Flood Control and Drought Relief. The Yangtze River Basin has had 15 percent more rain than normal, Duan Yihong, the director of the National Meteorological Center, told the U.K. Press Association.

Boat traffic through the Three Gorges Dam, the world’s largest hydropower plant, has been barred pending a second surge in water levels on the Yangtze that arrived early Wednesday morning, according to the BBC. The dam withstood its second test as water levels in the reservoir neared its maximum capacity of 175m because of heavy rainfall in the upper Yangtze.

The Three Gorges Dam has been built with the capacity to buffer and reduce the impact from flooding, and has, thus far, successfully contained the country’s biggest rolling rivers. Construction on Three Gorges began in 1994 and is scheduled to be officially completed in 2011. The dam experienced its first major test early last week, when the flow of the Yangtze River was at its highest level since it came online in 2009, Xinhua reports.

Last week’s peak flow rates were 70,000 cubic meters per second, while this week’s were around 56,000 cubic meters per second, Xinhua reports. In anticipation, officials increased the amount of water discharged through the dam’s spill gates—warning downstream residents of the increased stream flow.

Flooding has effected a large swath of country, with southern China battered by continual rainfall throughout the month of June. In the past two weeks, rainstorms have plagued the Shanxi, Sichuan, Hubei and Henan provinces in Central China with landslides as well as floods. These rainfall levels are the greatest Henan province has experienced in 100 years. The onslaught of storms caused a bridge to collapse in Henan over the weekend, killing at least 37, the Global Times reports.

More than 330 people have died since mid-July because of the rainstorms, according to the Ministry of Civil Affairs. As of Tuesday, 40 million people have been effected by the damage: with 140,000 homes destroyed, 417,000 hectares of crops decimated and 3.1 million people evacuated, Xinhua reports. Losses from the recent storms were estimated at $US7.78 billion, bringing the cumulative total to nearly $US26 billion.

Rain is expected to continue to batter the southeast, southwest and northeastern parts of China through today, the UKPA reports.